Storage battery charging system



Sept. 3, J 1935; l J. L. WOODBRIDGE ,0 8

STORAGE BATTERY CHARGING SYSTEM Filed Aug. 18, 1934 INVENTOR.

Patented Sept. 3, 1935 V UNITED STATES PATENT OFFl-CE s'ronaoc' BATTERYcnanomc SYSTEM Jersey Application August is, 1934. Serial No. 740,413 '3Claims. (Cl. 171-314) The invention relates to systems for controllingthe charge of a storage battery and is more particularly applicable tosystems in which'it is desired to cut of! the charging current when acertain battery voltage has been reached but to reconnect the battery tothe charging source if itshould subsequently be subjected to a furtherdischarge. The system is of particular advantage in controlling thecharge of a train-lighting storage battery at the terminal station andespecially a battery which is in air conditioning service and may becalled upon to carry the load of the air conditioning apparatus whilethe car is standing at the station just previous to its departure.

Under such conditions, if the battery requires apreliminary charge, itis customary to connect it to a source of harging current at theterminal station by means oia charging plug inserted in a suitablecharging receptacle mounted on the car and connected to the battery. Inorder to avoid the possibility of prolonged overcharge under theseconditions, it is desirable to provide an automatic switch which willopen the charging cir-' cult when the battery voltage rises to a pointcorresponding to the'approach to the fully charged condition. Such anautomatic switch can be controlled by a coil connected across thebattery circuit and so designed that, at a certain battery voltageapplied to the coil, the circuit will be opened but ii" the voltage ofthe battery drops to a point corresponding to a discharging condition,the charging circuit will again be closed and additional current besupplied to the battery and its load. In such a device, it is importantthat the coil, which isconnected across the battery to operate theautomatic switch, shall be automatically disconnected from the batteryexcept whenthe charging circuit is connected to the car, to avoid acontinuous drain from the battery when the car is out of use.

In order to accomplish these various objects, I have devised the schemeshown in the accompanying diagram, in which 3 indicates the bat teryconnected to the load circuit l-2 to which the lamps 8 and the motor 'Imay be connected. The battery is connected by means of conductors 4 andI to the charging receptacle I which is adapted to receive the chargingplug I connected by conductors II and II to any suitable sourceofchargingcurrent (not shown).

In the circuit of conductor 4 are interposed the contacts I! ofcontactor l3 whose exciting coil ll is connected across the battery byconductors II and It. In the circuit 01' conductor it are interposed thecontacts II oi a relay It provided with two exciting coils l9 and 20.Coil I9 which consists oi a few, comparatively heavy turns, is connectedin series with the charging circuit. 4, while coil 28, which consists ofa comparatively large number of=fine wire turns, is connected byconductors 2| and 22 across the contacts I! of contactor ii. Thecontacts I! are normally held closed by the spring 23.

The operation 01 this apparatus is as follows:

When the charging circuit is disconnected at 10 the charging plug 9,there will be no current flowing in either coil I9 or coil of the relayl8 and this relay will be in the open position shown in the diagram andno current will flow through the coil ll of contactor i3 and thecontacts at l2 will 16 remain closed. When it is desired to charge thebattery 3, the charging plug 9 will be inserted in the receptacle 8 and,by reason of the voltage maintained on the charging circuit I 0 l Iwhich will normally be higher than that of the battery, 24} chargingcurrent will flow into the battery, passing through coil l9 and acrossthe contacts II. This current in the coil l9 will close the contacts I!of the relay It, thus connecting coil ll of the contactor l3 across thebattery. Until, however, 26 the voltage of the battery reaches a certainpredetermined point corresponding to a condition of nearly full charge,the current in coil It will not be sufficient to open the contacts I2.When, however, this predetermined battery voltage is reached, 30 theefiectof the current in coil I4 will be sufllcient to open the contactsl2 and interrupt the charging current. This will interrupt the currentin the coil I 9 of relay II and, were it not for the excitation of coil20, the contacts at I! would be opened, causing the contactor l3 againto close the contacts I 2, reestablishing the charging current in coili9, thus producing a continuously repeated opening and closing of thetwo switches. However, as stated above, the current 49 in coil 20, whenthe contacts at' I! have been opened, due to the fact that the voltage01' the charging source is always higher than the voltage of thebattery, will hold the contacts I! of relay it closed, maintaining theexciting current in coil ll of contactor ii.

If now the load due to the lamps 6 and the motor I is thrown on thebattery, its voltage will drop until a point is reached where theexcitation When the charging plug 9 is removed from the receptacle 8,there will be no exciting currentin either coil l9 or coil 20 of relayl8 and the contacts at I! will be opened, thus cutting off the drain ofcurrent from the battery through coil I4.

I do not intend'to be limited save as the scope of the prior art and ofthe attached claims may require.

I claim:

1. Incombination, a storage battery and its load circuit, a chargingcircuit for the battery, .8, contactor having contacts interposed in thecharging circuit, means including a coil responsive to. the batteryvoltage for opening said contacts, and a relay having contacts foropening 2. In combination, a storage battery, a load circuit for saidstorage battery, a charging circuit for said storage battery, a sourceof electricity in said charging circuit, a normally closed contactorcontrolling said charging circuit, a coil for said contactor connectedacross said charging circuit, a switch controlling the connection ofsaid coil across said charging circuit, a second coil connected in saidcharging circuit in series with the contacts of said contactor andstressing said switch to closed position when said second coil isenergized, and a third coil connected in said charging circuit inparallel with the contacts of said contactor and stressing said switchto closed position when said third coil is energized.

3. In combination, a storage battery, a load circuit for said storagebattery, a charging circuit for said storage battery, a source ofelectricity in said charging circuit, a normally closed contactorcontrolling said charging circuit, a coil for said contactor connectedacross said charging circuit, a switch controlling the connection ofsaid coil across said charging circuit, a second coil consisting of afew turns of heavy wire connected in said charging circuit in serieswith the contacts of said contactor and stressing said switch to closedposition when said second coil is energized, and a third coil consistingof a number of turns of fine wire connected in said charging circuit inparallel with the contacts of said contactor and stressing said switchto closed position when said third coil is energized.

JOSEPH LESTER WOODBRIDGE.

